The present invention relates to a computer system, being applied to a personal computer capable of using an expanded unit, having a radiator for radiating heat of an interior of a computer main body.
In recent years, a portable small-sized personal computer has been developed as a data processor for a personal digital assistants (PDA) having multi-functions such as a communication function.
In addition to the miniaturization of the entire apparatus, improvement of calculation processing ability and various peripheral functions have been made in such a portable small-sized personal computer. Particularly, there has been developed a computer system, using an expanded unit (or an optional unit), which is called "docking station" or "port replicater", for expanding data processing function of the main body of the computer.
On the other hand, in the portable small-sized personal computer, since it is necessary to drive the computer by a built-in battery other than AC commercial power source, a saving of consumption power is required. Due to this, various kinds of saving systems are developed. In the recent small-sized personal computer, the saving of consumption power tends to be increased in accordance with the high performance and multi-function.
Generally, if the calculation processing ability of CPU is increased, the amount of heat in the computer is increased. As a result, an effective radiation mechanism is needed. As the radiation mechanism, a cooling fan and a heat sink are known. The heat sink is formed in the vicinity of a circuit board on which circuit elements such a CPU are mounted.
In the portable small-sized personal computer, it is difficult to ensure a space enough to provide the radiation mechanism other than the structural elements such as a circuit board in the housing body. Particularly, in a thin typed (notebook typed) small-sized personal computer, it is impossible to provide the cooling fan in view of the structure. Moreover, in the case of the radiation mechanism using the heat sink, since the surface area of the heat sink is limited, the radiation effect cannot be efficiently obtained.
Thus, in recent years, particularly, in the portable small-sized personal computer, there is a tendency that consumption power is increased in accordance with the multi-function and improvement of the calculation processing ability of CPU. On the other hand, it is difficult to provide the radiation mechanism for obtaining a sufficient radiation effect in order to miniaturize the main body of the apparatus.
If the radiation effect of the computer main body is insufficient, the processing ability of the computer main body cannot be performed at its maximum. Due to this, in the conventional case, for operating the circuit element, e.g., CPU, of the computer main body by the operation clock, the operation of the circuit element is limited as follows:
More specifically, the circuit element is operated for short time by a high speed operation clock. Or, the circuit element is operated for long time by a low speed operation. As a result, the performance of the computer system can be lowered than the performance, which is based on the design specification.